1. Field of the Invention
The present invention relates to a zoom lens and an image pickup apparatus including the same, which are suitable for an image pickup apparatus using an image pickup element, such as a video camera, an electronic still camera, a broadcasting camera, or a monitor camera, or an image pickup apparatus such as a silver-halide film camera.
2. Description of the Related Art
A zoom lens having a short total lens length (a distance from a first lens surface to an image plane), a high zoom ratio, and a high optical characteristic all over the entire zoom range is required for a photographing optical system for use in an image pickup apparatus. The zoom lens having a high zoom ratio has a tendency that in general, the entire system becomes large and the weight becomes heavy. When the zoom lens becomes large in size and heavy in weight, the zoom lens is vibrated due to camera shake or the like during the photographing in many cases, and hence the image blur is more liable to occur in the photographed image.
There is known a zoom lens in which a part of a lens system is shifted in a direction perpendicular to an optical axis, to thereby correct the image blur. In Japanese Patent Application Laid-Open No. H10-260356, in a four-unit zoom lens including, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power, the image blur is corrected by shifting the third lens unit.
In Japanese Patent Application Laid-Open No. H10-090601, in a five-unit zoom lens including, in order from an object side to an image side, first to fifth lens units having positive, negative, positive, negative, and positive refractive powers, respectively, the image blur is corrected by shifting the fourth lens unit. In addition, there is known a zoom lens in which a part of a lens system is rotated (tilted) with a point on an optical axis as a center, to thereby correct the image blur. In Japanese Patent Application Laid-Open No. H06-160778, in a four-unit zoom lens including, in order from an object side to an image side, first to fourth lens units having positive, negative, positive, and positive refractive powers, respectively, the image blur is corrected by tilting the first lens unit.
In addition, there is known a zoom lens aimed at reducing aberrations occurring during the image blur correction. In Japanese Patent Application Laid-Open No. 2012-141598, in a zoom lens including, in order from an object side to an image side, first to fourth lens units having positive, negative, positive, and negative refractive powers, respectively, a image stabilizing unit is provided within the fourth lens unit. In addition, a plurality of shift image stabilizing units are provided within the fourth lens unit, and the respective shift image stabilizing units are used properly depending on changes in a focal length.
In addition, there is known a zoom lens in which a image stabilizing unit as a part of a lens system is shifted in a direction perpendicular to an optical axis, and a image stabilizing unit is rotated with one point on an optical axis as a rotation center, to thereby correct the image blur. In Japanese Patent Application Laid-Open No. H05-232410, in a four-unit zoom lens including, in order from an object side to an image side, first to fourth lens units having positive, negative, positive, and positive refractive powers, respectively, an image blur is corrected by shifting and tilting the second lens unit.
In general, in order to carry out precisely the image blur correction and reduce an aberration variation during the image blur correction in the zoom lens having a image stabilizing function, it is important to appropriately set a lens configuration of the zoom lens, a lens configuration of the image stabilizing unit for the image blur correction, and the like. If the lens configuration of the image stabilizing unit, which is moved for the image blur correction is not proper, the image blur correction becomes insufficient, an amount of occurrence of a decentering aberration during the image stabilization becomes large, and it becomes difficult to maintain a high optical characteristic during the image stabilization.